It's also their interest and ability to adapt to the world outside of the nobility that allows them to survive:

but interestingly, dany's integration into the dothraki is one that allows her some degree of independence and self-determination - relatively, in contrast to before. it's a transformation that then allows her to take the mantle of leadership and queenship and embrace power, though it's a fraught thing - her ambitions of queenship are ones grounded in the view of the common people, in giving them plenty, but also requires her to balance the need for conquest required to attain power:

inversely, arya starts in a position of comfort, with all the love dany wishes she has - having the security and warmth of a loving family, having a strong sense of home welcoming her back (including nobles who'd rally for her and her name!), and in particular, an elder brother than would quite literally die for her freedom.

more interestingly, arya in some way is living out the fantasies dany has about being a 'normal child' - arya smears her face with dirt and mud to hide, arya runs like a common born child in the alleys and gutters, arya travels on a ship and learns sailor's knots, intermingles with them at the docks. she even returns to Braavos, the city of dany's childhood. but these adventures - the sorts of things arya used to think she wanted - haven't brought her much happiness. instead, she's lost herself in the fantasy of the dissolution of herself, in removing herself completely to remove herself from her grief, and it has brought her very little:

which i think - and this is some conjecture - but i think may signal the way things will go when daenerys attempts to find 'home' in westeros, again a fantasy that helps her justify the necessity of conquest and reclamation of the iron throne. but unlike arya stark, there are no bannermen rallying to dany's name there. there's no one secretly sewing dragons into their banners, there's no one so devoted to the stories of the targaryens as viserys wished they would. it's a fantasy! a dangerous fantasy. one that will likely take her further than her dreams of a kingdom where people are happy, with bellies full, one that will even take her further from dreams of travel and adventure and sailing, one that will not give her 'home', truly. daenerys targaryen might end up being someone far away from dany the girl (indeed, there's probably a contrast to be made here between dany v daenerys v mother and arya v all her various guises).